Field trial results with fensulfothion and trichloronate for control of grass grub ( Costelytra zealandica (White))

Abstract

Fensulfothion, trichlonmate, “Dursban”, and lindane were tested in two field trials against grass grub (Costelytra zealandica (White)) larvae in pasture, in comparison with DDT and diazinon. In one trial, with treatments applied in May, trichloronate was ineffective at rates up to 3 lbt per acre, and fensulfothion at 2 lb per acre gave only moderate effect. Sequential treatments were made with fensulfothion in the second trial. Application in March was highly effective, that in April was considerably less effective, and application in June was ineffective. It is suggested that the possible greater susceptibility to insecticides of second instar larvae (the predominant stage during, but not after, March) and their closer proximity to the soil surface than third instar larvae may account for this. “Dursban” and lindane applied in April were not effective in the year of application.